The Uize.Class module, that implements the class mechanism for the UIZE JavaScript Framework, has been improved with the addition of a once instance method for state properties.

SYNTAX

wiringsOBJ = myInstance.once (propertyNameSTR,handlerFUNC);

If the value of the property specified by the propertyNameSTR parameter is truthy when the once method is called, then the handler specified by the handlerFUNC parameter will be executed immediately. Otherwise, the value of the property will be watched and the handler will be executed once the property's value becomes truthy, upon which the property watcher will be removed and the property will no longer be watched. By design, the handler is only executed for the first time that the property's value becomes truthy.

The once method is useful when using a state property to represent a condition, and where you wish to register code that should be executed once the condition has been met, and immediately if the condition is already met at the time that the once method is called. Consider the following example...

EXAMPLE

myWidget.once (
  'wired',
  function () {
    // do something now that the widget has been wired
  }
);

In the above example, a handler is being registered to be executed once the widget myWidget has been wired (i.e. the value of its wired state property hecomes true).

1. Return Value